1. Field of Invention
This invention relates to programmable image processors, and more particularly to programmable image processors providing for the scanning of a received video image by a stored video image in one, or both, of two orthogonal directions.
2. Description of the Prior Art
The use of video image processors to continuously sample a scene of video and to compare the sampled scenes with a reference scene, have been known in the art in the form of intrusion alarm systems. Such systems detect differences in sampled video images and provide a suitable alarm indication. These systems however are limited to fixed, or stationary object images wherein features or light and dark regions remain fixed with respect to the reference image, and are in nearly perfect alignment. In fact, it is the exact purpose of the intrusion alarm systems to provide an indication of an intrusion into the field of view recorded in the video image, by detecting just such a misalignment of imaged features. The use of such systems in other applications, such as the inspection of the finished surface detail of successive manufactured objects of the same type appearing on a production assembly line, is impractical due to the exteme difficulty in insuring exact alignment of the successive objects within the image processor field of view. The difficulty in insuring successively aligned objects would necessarily result in excessively high error indications, whose number would be a direct function of the degree of misalignment, and which would unnecessarily cause a rejection of an otherwise properly finished, or manufactured object. The allowance of a high error count threshold to compensate for an allowed degree of misalignment of successive objects, results in a reduction in the resolute ability to detect surface imperfections, or errors in the manufactured object, and therefore a risk of a low quality production yield.